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1SIMPACK User Meeting, TOWER-MKS, November 2004
IST GmbH, Aachen
TOWER-MBSHydrodynamic bearings and sliders
in commercial MKS programs
Summary of Content:
0. IST-Company Profile
1. Introduction into TOWER-MKS- Overall Concept- User-Interface SIMPACK- Demonstration Application
2. Hydrodynamics Theory - Methods- Mixed Friction- Elasto-Hydrodynamics (EHD)
3. Application of Hydrodynamics- Hydrodynamics Input Parameters- Evaluation with XPost
positioning
slider
2
SIMPACK User Meeting, TOWER-MKS, November 2004
Program System Overview
IST Ingenieurgesellschaft für Strukturanalyse und Tribologie mbH
.
TOWER
COMO3D
FIRST
MKS -HYDRO
Program Systems FIRST, PIMO3D, COMO3D und TOWERStructure DynamicsTribologie
Load
Deformations, velocities, accelerationsHydrodynamic lubricant film pressure, solid body contact, friction losses, Gap course, shifting course, bearing deformationBearing loads, stress of components•
••
PIMO3DThe ‘IST GmbH’ was found in 1997 as spin-off of the ‘RWTH Aachen’and of the ‘Universität Kassel’ headed by Prof. Knoll. The IST is an engineering association with core competences in the development of computer-assisted simulation software as well as its application on structure dynamics/elastohydrodynamics coupled engine components. Areas of application are dimensioning, weak point analysis and system optimisation of tribological, structure dynamical and acoustical problems. An extensive cooperation exists at present with enginemanufactures and their suppliers. Furthermore, the IST is responsible for the maintenance of software that was developed as part of the FVV research projects of the ‘Institut für Maschinenelemente und Konstruktionstechnik’ of the University of Kassel.
Ø Solution of the Reynolds differential equation for rough surfaces in each period
Ø Optional bearing geometriesØ Consideration of the oil supplyØ Mixed friction (flow factors, contact pressure)
Sleeve Bearing Calculation
TOWER
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SIMPACK User Meeting, TOWER-MKS, November 2004
Ø Solution of the complete Reynolds equation in each period
Ø Piston- and bold hydrodynamicsØ Multi body system for illustration of large rigid
body motionsØ Complex production- and contour in operationØ Contour coverØ Partial filling status in the piston flow clearance Ø Mixed friction model based on flow simulations
(flow factors, contact pressure)
PIMO3D
Piston-Cylinder-Dynamics
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SIMPACK User Meeting, TOWER-MKS, November 2004
Ø Structure dynamic multiple body simulationØ Integration in the period (non-linear)Ø Complex FEM structures (~1.e6 FHG)
static/modal reduction (~150 FHG)Ø Rigid body dynamic (big motions)Ø Open model generation
2. Hydrodynamics Theory - Reynolds differential equation- Mixed Friction- Impedance Method- Online-FE-Method- Summary of all Methods
3. Application of Hydrodynamics- Hydrodynamics Input Parameters- Evaluation with XPost
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SIMPACK User Meeting, TOWER-MKS, November 2004
Hydrodynamic Methods Overview
Glo
bal E
last
icity
Loca
le E
last
icity
(EH
D)
Online-EHD with substructure technique- complex engine compound with bearingsn- substructures with main axis reduction- interface modes with SVD (boundary modes)- high locale precision in each bearing bore
Impedance Method (characteristics diagram solution)- interpolation in characteristic diagrams (very quick)- limited model generation(only cylindrical, no tilting, grooves, ...)
Online FEM-Method- solution of the Reynolds equation in each period- optional shell geometry (oil grooves, holes, etc)- variable gap in axial direction (tilting )
Offline-EHD (TOWER)- Input: shaft tilting and force from MBS- rear EHD-analysis (without reaction)
Online-EHD- compact single body (e.g. connection rod ) - main axis reduction for bores
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SIMPACK User Meeting, TOWER-MKS, November 2004
Mixed Friction Theory – Micro-Hydrodynamics
p 1
p 2
u 1
u 2
Micro hydrodynamics or rough surfaces
Hydrodynamic Lubricant Film Reaction
16 122 1 1r
W Wz
ht
p ps∂
∂ϕ η∂∂ϕ
∂∂ η
∂∂
∂∂
σ∂∂
∂∂
Φ ΦΦ∆h p
zh p
z6
hz
3 3
+
= + +
Reynoldssche Dgl.
Druckflußfaktor PΦ
/h σ
3P rauh
glatt
q hq h
Φ = ∗
Scherflußfaktor
/h σ
SΦS rauhq
u σΦ =
∗
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SIMPACK User Meeting, TOWER-MKS, November 2004
Umfangsfräsen
Läppen
Drehen
Schleifen
Honen
Funkenerosion
Stirnfräsen
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Φ P
[-]
Spaltweite hd [µm]
Druckflußsimulation- transversal
ideal glatte Oberfläche
Tragkraft-steigerung
ISO-Rauheitskennzahl N6R = 0.8 µma
Micro Hydrodynamics on different Editing
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SIMPACK User Meeting, TOWER-MKS, November 2004
Mixed Friction Theory – Solid Body Contact
Hydrodynamische Schmierfilmreaktion
16 122 1 1r
W Wz
ht
p ps∂
∂ϕ η∂∂ϕ
∂∂ η
∂∂
∂∂
σ∂∂
∂∂
Φ ΦΦ∆h p
zh p
z6
hz
3 3
+
= + +
Reynoldssche Dgl.
Festkörperkontakt
F F FHyd c= +
F f F µ Fr Hyd c c= +
Normalkraft
ReibungKontaktmodellIMK
Spaltweite h
p c Kontaktdruck integralStreubereich Greenwood/Tripp
3D-Oberfläche Kontaktdruck lokal
Gesamtdruckpges = p + pC
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SIMPACK User Meeting, TOWER-MKS, November 2004
pc[GPa]
Contact Pressure Characteristic Diagram pc(h*)
0
1
0 1 2 3 4
Ra=0,75[µm]
Ra=0,61[µm]
Ra=0,54[µm]
h* [µm]
New ConditionLow wearHigh wear
Test block experimentdragged:- F = 50N/mm2- n = 1500 1/min- T = 90 ° C
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SIMPACK User Meeting, TOWER-MKS, November 2004
1. Bearing coupling (gap function h)
2. Force coupling
Cone: • coupling node on the rotation axis• interpolated spline)
Shell:• coupling node in the bore• "least square fit" of a rigid cylinder (bore)
Cone:• local pressure forces on adjacent coupling nodes
Shell:• optimal force distribution (singular-value
decomposition)
Exact resulting loads Approximation of the pressure distribution
Hydrodynamic Coupling: Online-FEM
rigidcylinder
h
p
Fres
coupling nodes
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SIMPACK User Meeting, TOWER-MKS, November 2004
x
y
z
Fhyd
h
Coupling with rigid body Coupling with flexible body
σ Standard deviation (=Rq) h* nominal gap widthK Factor
(common size 1*10-3)
E here: Steel on both bodies
6.804* *54.4086 10 4 ; 4− ′= ⋅ ⋅ ⋅ ⋅ − <
c
h hp K Eσ σ
*hydrodynamic data, name = contactcontact pressure factor = 2.1e9 # calculate on contact pressurestandard deviation shell = 1.e-6 # [m] according to Rqstandard deviation shaft = 1.e-6 # [m] according to Rqfriction value = 0.05 # friction value according to
Coulomb
Geometric roughness average value
Contact Pressure
1 22 2
1 2 2 1
2(1 ) (1 )
⋅′ =− + −
E EEE Eν ν
Replacement-E-Module for both Contact Bodies
δ Profile deviationsΩ Roughness reference area
Consideration of Roughness according to Greenwood and Tripp
*Bearing
*Bearing Definition
*Hydrodynamic Data
*Bearing Segment
*Crush Relief
*Pressure Boundary Conditions
*Oil Supply*Roughness Chart
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SIMPACK User Meeting, TOWER-MKS, November 2004
XPost V6.0
Program XPost
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SIMPACK User Meeting, TOWER-MKS, November 2004
XPost V6.0
and local result dimensions :- Pressure distribution- Gap function- Oil output (hole def.)
Program XPost
Graphic interactive evaluation
of integral result dimensions:- Shifting course- Min. gap- Max. pressure- Friction capacity